Continuous belt for belt-type separator devices

ABSTRACT

A belt for use in a belt separation apparatus and a method to separate a particle mixture based on tribo-electric charging of particles is disclosed. The belt is particularly suitable for tribo-electric separation of particles that tend to accumulate on the edges of the belt separation apparatus and/or tend to compound, or blend, with the belt material. The belt comprises impermeable longitudinal edges, apertures interior to the longitudinal edges of the belt, and periodic notches formed in the longitudinal edges of the belt at periodic locations in the edge of the belt.

BACKGROUND

1. Field of Invention

The present invention relates to an improved belt that may be used in abelt separation apparatus to separate a particle mixture based ontribo-electric charging of the particles.

2. Discussion of Related Art

Belt separator systems (BSS) are used to separate the constituents ofparticle mixtures based on the charging of the different constituents bysurface contact (i.e. the triboelectric effect). FIG. 1 shows a beltseparator system 10 such as is disclosed in commonly-owned U.S. Pat.Nos. 4,839,032 and 4,874,507, which are hereby incorporated by referencein their entirety. One embodiment of belt separator system 10 includesparallel spaced electrodes 12 and 14/16 arranged in a longitudinaldirection to define a longitudinal centerline 18, and a belt 20traveling in the longitudinal direction between the spaced electrodes,parallel to the longitudinal centerline. The belt 20 forms a continuousloop which is driven by a pair of end rollers 22, 24. A particle mixtureis loaded onto the belt 20 at a feed area 26 between electrodes 14 and16. Belt 20 includes counter-current traveling belt segments 28 and 30moving in opposite directions for transporting the constituents of theparticle mixture along the lengths of the electrodes 12 and 14/16. Theonly moving part of the BSS is the belt 20. The belt is therefore acritical component of the BSS. The belt 20 moves at a high speed, forexample, about 40 miles an hour, in an extremely abrasive environment.The two belt segments 28, 30 move in opposite directions, parallel tocenterline 18, and thus if they come into contact, the relative velocityis about 80 miles an hour.

Related art belts were previously woven of abrasion resistant 45monofilament materials. These belts were quite expensive and lasted onlyabout 5 hours. The mode of failure was typically longitudinal wearstripes due to longitudinal wrinkling, that would wear longitudinalholes in the belt such that it would fall apart and catch on itself. Thestrands would also wear where they crossed and flexed in moving throughthe separator. The Applicant has made attempts to improve such beltswith different materials and different weaves in an attempt to find awoven material with a longer life. These attempts were unsuccessful.

An improvement over woven belts for BSS were belts made of extrudedmaterials, which have better wear resistance than woven belts and maylast on the order of about 20 hours in a BSS. An example of suchextruded belts is described in commonly-owned U.S. Pat. No. 5,819,946entitled “Separation System Belt Construction,” which is hereinincorporated by reference. Referring to FIG. 2, there is illustrated aschematic drawing of a section of an extruded belt 40. Control of thegeometry of extruded belts is desirable, but can be difficult to achievewith extruded belts.

One extruded belt that has been used in BSS is described incommonly-owned U.S. Pat. No. 5,904,253, which is also hereinincorporated by reference. Referring to FIG. 3, which illustrates anenlarged portion of the BSS shown in FIG. 1, the directions of thecounter-travelling belt segments 28, 30 are shown by arrows 34 and 36,respectively. As illustrated in FIG. 2-3, one example of a desired belt40 geometry (See FIG. 3) has a leading edge 43 of the belt 40 (See FIG.2) of the cross direction strands 46 is provided with an acute angle 44.

To improve the life of the extruded belt and to gain better control ofthe geometry of the belt profiles discussed in U.S. Pat. No. 5,904,253,a method of joining abrasion resistant thermoplastic sheets as describedin commonly-owned U.S. Pat. No. 6,942,752, herein incorporated byreference, has been used to produce belts from ultra high molecularweight polyethylene (UHMWPE) sheets. One example of a convenient methodfor forming the holes and leading edge and trailing edge features of adesired geometry in such UHMWPE sheets is to use a multi-axis machinetool. With this device, a sheet is loaded onto a table and a cutter headis moved across the sheet and each opening in the belt may be cutindividually. Through the proper choice of cutting tool, the holes canbe cut with leading edge and trailing edge features as desired. It isalso to be appreciated that the desired leading edge geometry can beobtained through other forming processes and devices such as molding,punching, machining, water jet cutting, laser cutting, and the like.

SUMMARY OF INVENTION

Aspects and embodiments are directed to an improved belt that may beused in a belt separation apparatus to separate a particle mixture basedon tribo-electric charging of the particles, and more specifically to animproved belt having notches in each impermeable longitudinal edge. Theimproved belt is particularly suitable for tribo-electric separation ofparticles that tend to accumulate on the edges of the belt separationapparatus and/or tend to compound, or blend, with the belt material.

One embodiment of a continuous belt for use in a belt separator systemfor separating components of a difficult-to-fluidize material comprisesimpermeable longitudinal edges, apertures interior to the longitudinaledges of the belt, and periodic notches formed in the longitudinal edgesof the belt at periodic locations in the edge of the belt.

According to aspects of this embodiment, the apertures are configured tobe permeable to the components of the difficult-to-fluidize material.According to aspects of this embodiment, the notches are configured forconveying the components of the difficult-to-fluidize material in adirection along the longitudinal direction of the belt and away from theedges of the belt separation system. According to aspects of thisembodiment, the notches are formed in the longitudinal edge of the belthave a beveled edge. According to aspects of this embodiment, the beveledge of each notch has a radius in a range of 4-5 mm. According toaspects of this embodiment, the notches formed in the longitudinal edgeof the belt have a triangular-shape. According to aspects of thisembodiment, the notches have an opening length is in the range of 19mm-400 mm. According to aspects of this embodiment, the notches have anopening depth is in the range of 13 mm-31 mm. According to aspects ofthis embodiment, the notches have a spacing is in the range of 63 mm-960mm. According to aspects of this embodiment, a leading edge of the notchhas an angle in a range from 12-45° with respect to the longitudinaledge. According to aspects of this embodiment, a trailing edge of thenotch is perpendicular with respect to the longitudinal edge. Accordingto aspects of this embodiment, the notches in the longitudinal edgeshave dimensions selected to maximize throughput of a belt separatorsystem for a difficult-to-fluidize material. According to aspects ofthis embodiment, the notches in the longitudinal edges have dimensionsselected to minimize frictional heating of the belt longitudinal edgestrands. According to aspects of this embodiment, the notches in thelongitudinal edges have dimensions selected to maximize an operatinglifetime of the belt for a difficult-to-fluidize material. According toaspects of this embodiment, the belt has a width a few mm less than awidth of the inside of the belt separator system.

One embodiment of a method of making a continuous belt for use in a beltseparator system for separating components of a difficult-to-fluidizematerial, comprises forming a continuous belt with impermeablelongitudinal edges, forming apertures interior to the longitudinal edgesof the belt that are configured to be permeable to the components of thedifficult-to-fluidize material, and forming periodic notches in thelongitudinal edges of the belt at periodic locations in the edge of thebelt.

According to aspects of this embodiment, the apertures are configuredfor conveying the components of the difficult-to-fluidize material in adirection along the longitudinal direction of the belt. According toaspects of this embodiment, the notches are formed in the longitudinaledge of the belt with a beveled edge. According to aspects of thisembodiment, the beveled edge of each notch with is formed with a radiusin a range of 4-5 mm. According to aspects of this embodiment, thenotches are formed in the longitudinal edges of the belt with atriangular-shape. According to aspects of this embodiment, the notchesare formed in the longitudinal edges of the belt with a leading edgehaving an angle in a range from 12-45° with respect to the longitudinaledge. According to aspects of this embodiment, the notches are formed inthe longitudinal edges of the belt with a trailing edge of the notchbeing perpendicular with respect to the longitudinal edge. According toaspects of this embodiment, the notches are formed in the longitudinaledges of the belt with dimensions selected to maximize throughput of abelt separator system for a difficult-to-fluidize material. According toaspects of this embodiment, the notches are formed in the longitudinaledges of the belt with dimensions selected to maximize an operatinglifetime of the belt for a difficult-to-fluidize material. According toaspects of this embodiment, the belt width is formed with a width thatis a few mm short of a width of an inside of the belt separator system.According to aspects of this embodiment, the continuous belt is formedby any of extruding, molding, punching, machining, water jet cutting,and laser cutting. According to aspects of this embodiment, the notchesin the longitudinal edges of the belt are formed by any of extruding,molding, punching, machining, water jet cutting, and laser cutting.

One embodiment of a continuous belt for use in a belt separator systemfor separating components of a difficult-to-fluidize material comprisesa first electrode and a second electrode arranged on opposite sides of alongitudinal centerline and configured to provide an electric fieldbetween the first and second electrodes, a continuous belt havingimpermeable longitudinal edges and apertures interior to thelongitudinal edges that are permeable to the components of thedifficult-to-fluidize material, and having periodic notches formedwithin the longitudinal edges at periodic locations in the edge of thebelt.

According to aspects of this embodiment, the apertures are configuredfor conveying components of the difficult-to-fluidize material havinglike net influenceability to the electric field in respectivecounter-current streams along the longitudinal direction between thefirst and second electrodes. According to aspects of this embodiment,the notches are configured for conveying the components of thedifficult-to-fluidize material in a direction along the longitudinaldirection of the belt separator system. According to aspects of thisembodiment, the notches formed in the longitudinal edge of the belt havea beveled edge. According to aspects of this embodiment, the bevel edgeof each notch has a radius in a range of 4-5 mm. According to aspects ofthis embodiment, the notches formed in the longitudinal edge of the belthave a triangular-shape. According to aspects of this embodiment, aleading edge of the notch has an angle in a range from 12-45° withrespect to the longitudinal edge. According to aspects of thisembodiment, a trailing edge of the notch is perpendicular with respectto the longitudinal edge. According to aspects of this embodiment, thebelt includes counter-current belt segments traveling in oppositedirections along the longitudinal direction. According to aspects ofthis embodiment, the notches in the longitudinal edges have dimensionsselected to maximize throughput of the belt separator system for adifficult-to-fluidize material. According to aspects of this embodiment,the notch in the longitudinal edge has dimensions selected to maximizean operating lifetime of the belt for a difficult-to-fluidize material.According to aspects of this embodiment, the belt has a width a few mmshort of a width of the inside of the belt separator system and theedges in the longitudinal edges of the belt are configured to sweepcomponents of the difficult-to-fluidize material away from the insideedge of the separation system.

One embodiment of a method of separating components of adifficult-to-fluidize material with a separation chamber having anelongated dimension that is long compared to a spacing between a pair ofopposing electrode surfaces, comprises providing an electric field beingbetween the opposing electrode surfaces, conveying the components of thedifficult-to-fluidize material in two streams in opposite directionsbetween the opposing electrode surfaces with a continuous conveying belthaving impermeable longitudinal edges and apertures interior to theimpermeable longitudinal edges that are permeable to the components ofdifficult-to-fluidize material, and conveying the components of thedifficult-to-fluidize material away from interior longitudinal sides ofthe separation chamber with notches periodically disposed in thelongitudinal edges.

According to aspects of this embodiment, the notches are configured toconvey the mixture of particles in a direction parallel to the opposingelectrode surfaces. According to aspects of this embodiment, the notchesin the longitudinal edges of the belt are configured to sweep an insidesurface of the longitudinal edges of the separation chamber. Accordingto aspects of this embodiment, the notches in the longitudinal edges ofthe belt have a beveled edge. According to aspects of this embodiment,the notches in the longitudinal edges of the belt have a radius in arange of 4-5 mm. According to aspects of this embodiment, the notches inthe longitudinal edges of the belt have a triangular-shape. According toaspects of this embodiment, the notches in the longitudinal edges of thebelt have a leading edge having an angle in a range from 12-45° withrespect to the longitudinal edge. According to aspects of thisembodiment, the notches in the longitudinal edges of the belt have atrailing edge that is perpendicular with respect to the longitudinaledge. According to aspects of this embodiment, the notches in thelongitudinal edges of the belt have dimensions selected to maximizethroughput of the belt separator system for a difficult-to-fluidizematerial. According to aspects of this embodiment, the notches in thelongitudinal edges of the belt have dimensions selected to maximize anoperating lifetime of the belt for a difficult-to-fluidize material.

One embodiment of a method of separating different components of adifficult-to-fluidize material in a separation chamber comprisesadmitting the difficult-to-fluidize material into the separation chamberhaving confronting surfaces spaced more closely than respective lengthsof the confronting surfaces, impressing a separation influence toward atleast one of the confronting surfaces of the separation chamber,separating the different components of the difficult-to-fluidizematerial in the direction of the separation influence according to theirrelative influenceability to the separation influence, mechanicallymoving the components of like net influenceability of thedifficult-to-fluidize material near each other in streams movingtransversely to the separation influence along the longitudinaldirection between the first and second electrodes, the streams being incommunication parallel to the separation influence so as to transfer aportion of at least one of the streams to another of the streams byvirtue of the continued action of the separation influence as thestreams progress transversely to the separation influence; and removingseparated streams of the difficult-to-fluidize material from theseparation chamber. The components of like net influenceability of thedifficult-to-fluidize material are mechanically moved by the continuousbelt having impermeable longitudinal edges of a predefined width andapertures interior to the longitudinal edges that are permeable to thecomponents of the difficult-to-fluidize material, and periodic notchesformed within the longitudinal edges at periodic locations in the edgeof the belt.

According to aspects of this embodiment, the notches are configured forconveying the components of streams of the difficult-to-fluidizematerial in a direction along the longitudinal direction of the beltseparator system. According to aspects of this embodiment, an insidesurface of the longitudinal edges of the separation chamber is sweptwith the longitudinal edges including the notches of continuous belt.According to aspects of this embodiment, the notches in the longitudinaledges of the belt have a beveled edge. According to aspects of thisembodiment, the notches in the longitudinal edges of the belt have aradius in a range of 4-5 mm. According to aspects of this embodiment,the notches in the longitudinal edges of the belt have atriangular-shape. According to aspects of this embodiment, the notchesin the longitudinal edges of the belt have a leading edge having anangle in a range from 12-45° with respect to the longitudinal edge.According to aspects of this embodiment, the notches in the longitudinaledges of the belt have a trailing edge of the notch perpendicular withrespect to the longitudinal edge. According to aspects of thisembodiment, the notches in the longitudinal edges of the belt havedimensions selected to maximize throughput of the belt separator systemfor a difficult-to-fluidize material. According to aspects of thisembodiment, the notches in the longitudinal edges of the belt havedimensions selected to maximize an operating lifetime of the belt for adifficult-to-fluidize material. According to aspects of this embodiment,the components of the streams of the difficult-to-fluidize material aremoved by the apertures in the interior region of the belt and by notchesin the longitudinal edge of the belt toward the longitudinal centerlineof the belt separator system and away from the first and secondelectrodes and away from the edges of the separation chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of at least one embodiment are discussed below withreference to the accompanying figures, which are not intended to bedrawn to scale. The figures are included to provide illustration and afurther understanding of the various aspects and embodiments, and areincorporated in and constitute a part of this specification, but are notintended as a definition of the limits of the invention. Where technicalfeatures in the figures, detailed description or any claim are followedby references signs, the reference signs have been included for the solepurpose of increasing the intelligibility of the figures anddescription. In the figures, each identical or nearly identicalcomponent that is illustrated in various figures is represented by alike numeral. For purposes of clarity, not every component may belabeled in every figure. In the figures:

FIG. 1 illustrates a diagram of one example of belt separator system(BSS);

FIG. 2 illustrates a plan view of an extruded belt

FIG. 3 illustrates an enlarged view of portion of current belt and BSS

FIG. 4 illustrates a plan view of an extruded belt;

FIG. 5A illustrates an enlarged plan view of a belt edge with atriangular edge notch that is beveled and with blanked hole adjacent tonotch;

FIG. 5B illustrates an side view of the belt of FIG. 5A;

FIG. 6. illustrates an enlarged plan view of a belt with a semi-circularedge notch;

FIG. 7. illustrates an enlarged plan view of a belt edge with a long,extended edge notch;

FIG. 8. illustrates an enlarged plan view of a belt edge illustratingedge notch spacing; and

FIG. 9. illustrates an enlarged plan view of a belt edge havingdifferent edge notch spacing.

DETAILED DESCRIPTION

Aspects and embodiments are directed to an improved belt that may beused in a belt separation apparatus to separate a particle mixture basedon tribo-electric charging of the particles, and more specifically to animproved belt having notches in each impermeable longitudinal edge. Theimproved belt is particularly suitable for tribo-electric separation ofparticles that tend to accumulate on the edges of the belt separationapparatus and/or tend to compound, or blend, with the belt material. Theimproved belt also results in an improved separation process, improvedbelt lifetime, reduced failure of the belt and less down time for theseparation apparatus.

It is to be appreciated that embodiments of the methods and apparatusesdiscussed herein are not limited in application to the details ofconstruction and the arrangement of components set forth in thefollowing description or illustrated in the accompanying drawings. Themethods and apparatuses are capable of implementation in otherembodiments and of being practiced or of being carried out in variousways. Examples of specific implementations are provided herein forillustrative purposes only and are not intended to be limiting. Also,the phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use herein of“including,” “comprising,” “having,” “containing,” “involving,” andvariations thereof is meant to encompass the items listed thereafter andequivalents thereof as well as additional items. References to “or” maybe construed as inclusive so that any terms described using “or” mayindicate any of a single, more than one, and all of the described terms.Also, the phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. Any references toembodiments or elements or acts of the systems and methods hereinreferred to in the singular may also embrace embodiments including aplurality of these elements, and any references in plural to anyembodiment or element or act herein may also embrace embodimentsincluding only a single element. References to “or” may be construed asinclusive so that any terms described using “or” may indicate any of asingle, more than one, and all of the described terms. Any references tofront and back, left and right, top and bottom, upper and lower, andvertical and horizontal are intended for convenience of description, notto limit the present systems and methods or their components to any onepositional or spatial orientation.

Referring to FIG. 4, one current design of a UHMWPE belt 45 has straightand smooth machine direction edge strands 47 that are thicker than themachine direction strands 42 or the cross direction strands 46 in theinterior of the belt. These wider (20-30 mm) edge strands 47 serve tocarry more of the tension load, provide dimensional stability and reducethe incidence of belt failure by edge 49 abrasion.

These UHMWPE sheet belts 45 have proven to have much longer life thanthe aforementioned extruded belts (See FIG. 2). In certain applications,such as the separation of unburned carbon from coal combustion fly ash,these UMHWPE belts have had been tested and shown to have a maximum lifeof up to 1950 hours before failure.

The fluidization characteristic of powders is one parameter indetermining how the particles of the powder are conveyed and separatedin a BSS. Section 3.5 in Pnuematic Conveying of Solids by Klinzig G. E.et al., second edition 1997, describes materials loosely as“fluidizable” or “difficult to fluidize”. This property is qualitativelyassessed by the behavior of the material in a fluidized bed. Thefluidization property of powders is generally accepted to be influencedby the powder particle size, specific gravity, particle shape, surfacemoisture, and by other less well understood properties. Coal combustionfly ash is an example of an easily fluidizable powder. Many otherindustrial mineral powders are more difficult to fluidize than fly ash.

The embodiment of the BSS with a continuous counter current belt movingbetween two longitudinal, parallel planar electrodes has inside edges ofthe separation chamber that are not directly swept by the belt 45. It isdesirable to minimize the area of the unswept zone of the edges of theseparation chamber, since it represents electrode area that is noteffective for particle separation. However, it is also typical to leavea gap between the edge 47 of the belt 45 and the inside edge of theseparation chamber to prevent the belt from rubbing and wearing againstthe inside edge of the separation chamber, which could lead to earlybelt failure. Therefore the width w (See FIG. 4) of the belt 45 isapproximately 20 mm narrower than the width of the separation chamber,in order to leave about 10 mm clearance between the inside wall of theseparation chamber and the edges 47 of the belt 45.

Fluidizable powders, such as coal combustion fly ash, are effectivelyswept from the inside edges of the separation chamber by the motion ofthe belt 45. This occurs because the motion of the belt 45 creates ashear force which exceeds the inter-particle forces between particles ofthe coal combustion flyash and between particles of the combustionflyash and the edge walls of the separation chamber. However, for“difficult to fluidize” or more cohesive powders, such as manyindustrial minerals, the shear force generated by the moving belt 45 isnot typically sufficient to overcome the interparticle forces in thepowder, which results in a build-up of compacted, thermally insulating,abrasive powder on the inside edge of the separation chamber in the zonebetween the inside wall of the separation chamber and the edges 47 ofthe belt 45 that the belt 45 does not sweep.

Such non-fluidized abrasive powder that can also become trapped, orsandwiched, between the machine direction edge strands 42 of the topsection of the belt 30 and the bottom section of the belt 28 (See FIG.2) which are moving in opposite directions at relative velocities from20 to 100 ft/sec. The abrasion between the moving belt segments,enhanced by the non-fluidized abrasive powder, leads to small fragmentsof UHMWPE belt being removed from the belt and frictional heating of theedge strands 47 over their width and along their length. At theseelevated temperatures, the small fragments of plastic belt material andthe powder tend to fuse together to form composites of powder andplastic, which can grow to 10-200 mm in length and 5-25 mm wide. Withthe edge of the belt 47 now running against these plastic-powdercompound deposits, they cause further frictional heating and eventuallydestroy the edge of the belt, sometimes even fusing the belt strandstogether. The composition of a typical thermoplastic-powder compositethat was retrieved from a belt failure caused by the buildup of thiscomposite residue has been measured as approximately 50% thermoplasticand 50% industrial mineral powder. This phenomenon of plastic powdercomposite buildup and accumulation on the unswept edges 47 of the BSSseparation chamber has led to extremely short belt life in the range oftens of hours for the BSS when processing some industrial minerals(particularly non-fluidized materials).

Referring to FIG. 5A, there is illustrated a plan view of an improvedbelt for a BSS, particularly for processing and separating someindustrial materials (particularly non-fluidized materials). To improvebelt life when processing “difficult to fluidize” particles using a BSS,the improved belt design 50 has been provided with continuous (having awidth w1 of 20-30 mm wide) edge strands 47 on each side of the belt(only one side of the belt is illustrated), which have been modified bycreating open notches 52 of a prescribed shape and location. Thesenotches 52 can be obtained through various forming means such asmolding, punching, machining, water jet cutting, laser cutting, and thelike.

The edge notches 52 provide a mechanism, pathway and conveying mechanismfor powder sandwiched between edge strands 47 of oppositely moving beltsegments 28, 30 to convey the particles of powder in either direction ofbelt motion. It is to be appreciated that the removal of stagnant powderbetween the edge strands 47 of oppositely moving belt segments 28, 30significantly reduces abrasion and frictional heating. This belt 50having such edge notches 52 has been tested in existing BSS of FIG. 1,and it has been shown that the use of belts with notched edges 52 haseliminated the formation of the plastic-powder composite build-upmaterial that has historically resulted in short belt file. This belt 50having such edge notches 52 has been tested in existing BSS of FIG. 1,and it has been shown that the belt life for has increased to 100's ofhours when processing “difficult to fluidize” industrial mineralpowders. This compares to belt life in the 10's of hours for prior artextruded belts having straight edge strands 47 without any notches, suchas shown in FIG. 4. The trailing edge 54 of the notch 52 perpendicularto the edge of the belt 49 and the direction the belt is moving 41provides a motive force to move powder in the direction of the beltmotion. The volume of the notch 52, which is determined by depth ofnotch D, length of notch L, angle Ø, and thickness t of the belt (SeeFIG. 5B), provides the carrying capacity of each notch 52. The spacingbetween notches (S) determines the carrying capacity of the belt perunit belt length of the belt. FIG. 5B illustrates a side view of thebelt 50 and the notch 52, and in particular illustrates that the edgesof the notch, such as the trailing edge 46, can be provided we a bevelhaving a bevel radius of b.

Example 1

In one example, separator belts 45 illustrated in FIG. 4 containing nonotches 52 and a continuous, unbroken, straight edge geometry 47 with awidth (w) of 25 mm was operated in a belt type electrostatic separatorsystem (BSS) while processing ground calcium carbonate material, adifficult to fluidize powder. These belts failed due to edge depositcompounding after a maximum of 15 hours of total operation. Belts 50 ofFIG. 5 containing triangular shaped edge notches 52 were operated on thesame difficult to fluidize mineral powder. Belts containing thetriangular-shaped edge notches 52 operated 20 times longer than the belt45 without the edge notches, and very rarely failed due to edgedeposits. Only 1 edge deposit failure was observed out of 21 belts 50operated with edge notches 52. This significant increase in operatinglife of the separator belt 50 is advantageous for reducing costs whenoperating a BSS. The dimensions of the belts used in this example arelisted below with dimensions referenced to FIG. 4.

No Edge With Dimensions Notches Triangular Edge Feature (ref. FIG. 5)(ref. FIG. 4) Notches Thickness t 3-4 mm 3-4 mm Edge Width (W) D + f 25mm 25 mm Notch Opening L N/A 33 mm Notch Spacing S N/A 100 mm NotchDepth D N/A 19 mm Solid Width f 25 mm 6 mm Notch Angle Ø N/A 45 degreesBevel Radius b N/A 4-5 mm Ultimate Belt 4 - Edge 20 - Not Edge FailureMode Compounding Compounding 1 - Edge Compounding Highest Belt Life 15hours 300 hours

Example 2

FIG. 6 illustrates another example of a improved belt 60 having beveledbelt edge notches 62 cut with a semi-circular pattern into edge 49 ofthe separator belt edge strand 47 with a standard edge thickness of 25mm. (FIG. 5) The semi-circular notches were cut with a smaller notchdepth (D) than the notches described in example 1, but the belt andnotches were still effective in preventing the edge buildup of the samedifficult to fluidize powder that has been observed with belts withoutnotches. The Belt Life of this embodiment was not as good at the beltlife of the belt with the triangular-shaped notches as of Example 1.Thus, it is apparent from this Example 2 and Example 1, that a varietyof edge notch configurations or shapes can be utilized to prevent edgedeposit compounding, and that the shape of notch affects the improvementin the belt life. The optimum notch dimensions for a particular powdercan be determined empirically by testing various belt notch designs.

Dimensions No Edge Notches Semi-Circular Feature (ref. FIG. 6) (ref.FIG. 4) Notches Thickness t 3-4 mm 3-4 mm Edge Width (W) D + f 25 mm25-44 mm Notch Opening L N/A 19 mm Notch Spacing S N/A 63 mm Notch DepthD N/A 13 mm Solid Width f 25 mm 12-31 mm Notch Radius r N/A 13 mmUltimate Belt Failure 4 - Edge 2 - Not Edge Mode Compounding CompoundingHighest Belt Life 15 hours 96 hours

Example 3

FIG. 7 illustrates another example of a belt 70, wherein the notchgeometry was varied by cutting a large continuous notch 72 of length (L)of 700 mm, with beveled edges to avoid a damaging catch of the beltnotch against a belt notch travelling in the opposing direction (FIG.7). This belt was operated while processing ground calcium carbonatematerial, a difficult to fluidize powder, during which time no evidenceof edge deposits or compounding was observed. From this example it isevident that notches with different lengths are effective in preventingedge deposit compounding. The optimum notch dimensions for a particularpowder can be determined empirically by testing various belt notchdesigns.

Dimensions No Edge Notches Extended Length Feature (ref. FIG. 7) (ref.FIG. 4) Notches Thickness t 3-4 mm 3-4 mm Notch Opening L N/A 400 mmNotch Spacing S N/A 960 mm Notch Depth D N/A 31 mm Solid Width f 25 mm25 mm Notch Angle Ø N/A 12 degrees Bevel Radius b N/A 4-5 mm UltimateBelt 4 - Edge 1 - Not Edge Failure Mode Compounding Compounding HighestBelt Life 15 hours 93 hours

Example 4

FIG. 8 illustrates another example of a belt 80, for which the spacing(S) of the notches was investigated by varying the frequency andlocation of triangular-shaped belt notches 82 along the length of thebelt. Notches with length (L) 33 mm and spacing (S) of 100 mm were cutinto the side of several belts in an uninterrupted pattern. Notches ofthe same geometry were cut into a second set of belts in a repeatingpattern of a notched section and a straight sidewall section with 4notches of length (L) 33 mm and spacing (S) of 183 mm into a 730 mm longsection, followed by an 820 mm long section of belt containing nonotches (See FIG. 9). This pattern was repeated throughout the length ofthe entire belt. From this example it is evident belts with increasedspacing between notches are effective in preventing edge depositcompounding. The optimum notch spacing for a particular powder can bedetermined empirically by testing various belt notch designs.

Notches Notches in Dimensions No Edge Spaced Every Alternating Sections(ref. FIG. Notches 100 mm Increased Spacing Feature 8) (ref. FIG. 4)(FIG. 8) (FIG. 9) Thickness t 3-4 mm 3-4 mm 3-4 mm Edge Width (W) D + f25 mm 22-44 mm 25 mm Notch Opening L N/A 19 mm 30 mm Effective Notch SN/A 100 mm 388 mm Spacing Notch Depth D N/A 11 mm 17 mm Solid Width f 25mm 10-32 mm 21 mm Notch Angle Ø N/A 45 deg 45 deg Bevel Radius b N/A 4-5mm 4-5 mm Ultimate Belt 4 - Edge 2 - Not Edge 4 - Not Edge Failure ModeCompounding Compounding Compounding Highest Belt Life 15 hours 64 hours124 hours

Example 5

Referring to FIG. 4, in another example, the importance of the belt edgenotches was demonstrated by testing a belt containing no edge notches,but a smaller edge width (W)=(D+f) of only 11 mm as compared to 25 mm.Both belt edge geometries were operated while processing ground calciumcarbonate material, a difficult to fluidize powder, and failedprematurely due to edge deposit compounding. This example illustratesthe importance of edge notches to process difficult to fluidize mineralpowders. Furthermore edge notches allow for thicker belt edge strands,which increase the resistance to stretching and allow for longer beltoperating life prior to stretch failure.

No Notches - No Notches - 25 mm 11 mm Feature FIG. 4 Edge Width EdgeWidth Thickness t 3-4 mm 3-4 mm Edge Width (W) D + f 25 mm 11 mm SolidWidth f 25 mm 11 mm Ultimate Belt Failure 4 - Edge 2 - Edge ModeCompounding Compounding Belt Life Average 15 hours 20 hours

Extensive work has been conducted to determine the optimum notchgeometry. In all cases notched edge belts operated significantly longerthan straight edge belts, and prevented edge compounding leading topremature belt failure. It should be appreciate that after many hours ofoperation the belt edge can wear, reducing the notch depth and length.As a result, the geometry of the belt notches can change with time.Therefore, the dimensions provided in the examples are not intended torepresent all possible notch dimensions, and that other notch dimensionsare possible and are within the scope of the invention.

One newly observed mode of separator belt failure when operating a BSSwith a notched edge belt is notch tearing. For notches with a large openarea, a narrow, longitudinal strand (f) is created between the insideedge of the notch and first hole opening in the body of the belt. Duringoperation, the edge 49 of the belt is rubbing against either thecompacted, abrasive powder that has accumulated on the unswept edges ofthe separation chamber, or the edges of the separation chamber itself.The edge of the belt rubbing at high velocity creates a shear stress,which stress if it exceeds the yield stress of the narrow longitudinalstrand (f) between the inside of the notch and the first hole opening inthe body of the belt, will cause the narrow, longitudinal strand (f) tostretch and break. This breaking of the narrow longitudinal strand isfacilitated by the flex fatigue of the plastic at the narrowest jointbetween the notch and the adjacent hole as it is repeatedly flexed up tosix times per second as it moves through the tensioning and drivesystem. The broken longitudinal strand (f) can create “catch” point forthe belt on its edge, which will lead to premature belt failure. Thetensile strength of the strand can be increased by increasing thethickness (t) of the strand. An alternative solution is to eliminate thenarrow strand by omitting or creating a blank (illustrated in FIG. 5A)of the first hole in the body of the belt nearest to the edge notch.

Having thus described certain embodiments of a continuous belt, methodof making the same, a separation system using such belt, and a method ofseparation, various alterations, modifications and improvements will beapparent to those of ordinary skill in the art. Such alterations,variations and improvements are intended to be within the spirit andscope of the application. Accordingly, the foregoing description is byway of example and is not intended to be limiting. The application islimited only as defined in the following claims and the equivalentsthereto.

What is claimed is:
 1. A belt separator system for separating componentsof a difficult-to-fluidize material, the belt separator systemcomprising: a first electrode and a second electrode arranged onopposite sides of a longitudinal centerline and configured to provide anelectric field between the first and second electrodes; a continuousbelt having impermeable longitudinal edges of a predefined width andapertures interior to the longitudinal edges that are permeable to thecomponents of the difficult-to-fluidize material, the belt configuredfor conveying components of the difficult-to-fluidize material underinfluence of the electric field-in respective counter-current streamsalong the longitudinal direction between the first and secondelectrodes; and the belt having periodic notches formed within thelongitudinal edges at periodic locations in the edge of the belt, thenotches being configured for conveying the components of thedifficult-to-fluidize material in a direction along the longitudinaldirection of the belt separator system.
 2. The system of claim 1,wherein the notches formed in the longitudinal edge of the belt have abeveled edge.
 3. The system of claim 2, wherein the bevel edge of eachnotch has a radius in a range of 4-5 mm.
 4. The system of claim 1,wherein the notches formed in the longitudinal edge of the belt have atriangular-shape.
 5. The system of claim 1, wherein a leading edge ofeach notch has an angle in a range from 12-45° with respect to thelongitudinal edge.
 6. The system of claim 1, wherein a trailing edge ofeach notch is perpendicular with respect to the longitudinal edge. 7.The system of claim 1, wherein the belt includes counter-current beltsegments traveling in opposite directions along the longitudinaldirection.
 8. The system of claim 1, wherein the notches in thelongitudinal edges have dimensions selected to maximize throughput ofthe belt separator system for a difficult-to-fluidize material.
 9. Thesystem of claim 1, wherein each notch in the longitudinal edge hasdimensions selected to maximize an operating lifetime of the belt for adifficult-to-fluidize material.
 10. The system of claim 1, wherein thebelt has a width a few mm short of a width of the inside of the beltseparator system and the edges in the longitudinal edges of the belt areconfigured to sweep components of the difficult-to-fluidize materialaway from the inside edge of the separation system.